Private Internet Access Extension Credential Leak via Basic Auth Handler

Executive Summary

CVE-2026-120627 is a vulnerability in the Private Internet Access (PIA) Firefox extension where an improperly guarded authentication handler leaks PIA proxy credentials. When a user visits a malicious site that issues a Basic auth challenge, the extension's authHandler blindly returns the user's proxy credentials without verifying the request's legitimacy. This exposes the full authentication token, allowing attackers to reconstruct it and potentially de-anonymize the user or route traffic through the victim's PIA account.

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Detection Guidance

Check the installed version of the Private Internet Access Firefox extension. If it is version 4.0.5 or later, the vulnerability may be present. Look for unexpected proxy authentication prompts or credential prompts from untrusted websites.

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Impact Analysis

This vulnerability can allow attackers to steal your PIA authentication token, which may lead to de-anonymization, unauthorized access to your PIA account, or traffic being routed through your account. Attackers could reconstruct the token from leaked credentials and use it to impersonate you or access your VPN services without consent.

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Compliance Impact

This vulnerability could lead to unauthorized access to user credentials, potentially exposing sensitive data. For GDPR, this may violate principles of data protection and user privacy. For HIPAA, it risks unauthorized access to protected health information if credentials are used to route traffic through a user's account.

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Mitigation Strategies

Disable or uninstall the Private Internet Access Firefox extension immediately. Avoid using the extension until a patched version is released. Monitor network traffic for unauthorized proxy authentication requests.

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